Flood inundation modeling using MIKE FLOOD and remote sensing data

A coupled 1D-2D hydrodynamic model, MIKE FLOOD was used to simulate the flood inundation extent and flooding depth in the delta region of Mahanadi River basin in India. Initially, the 1D model MIKE 11 was calibrated using river water level and discharge data of various gauging sites for the monsoon period (June to October) of the year 2002. Subsequently, the calibrated set up was validated using both discharge and water level data for the same period of the year 2001. The performance of calibration and validation results of MIKE 11 were evaluated using different performance indices. A bathymetry of the study area with a spatial resolution of 90m was prepared from SRTM DEM and provided as an input to the 2D model, MIKE 21. MIKE 11 and MIKE 21 models were then coupled using lateral links to form the MIKE FLOOD model set up for simulating the two dimensional flood inundations in the study area. Flood inundation is simulated for the year 2001 and the maximum flood inundation extent simulated by the model was compared with the corresponding actual inundated area obtained from IRS-1D WiFS image.     

A review on reflective remote sensing and data assimilation techniques for enhanced agroecosystem modeling

During the last 50 years, the management of agroecosystems has been undergoing major changes to meet the growing demand for food, timber, fibre and fuel. As a result of this intensified use, the ecological status of many agroecosystems has been severely deteriorated. Modeling the behavior of agroecosystems is, therefore, of great help since it allows the definition of management strategies that maximize (crop) production while minimizing the environmental impacts. Remote sensing can support such modeling by offering information on the spatial and temporal variation of important canopy state variables which would be very difficult to obtain otherwise.In this paper, we present an overview of different methods that can be used to derive biophysical and biochemical canopy state variables from optical remote sensing data in the VNIR-SWIR regions. The overview is based on an extensive literature review where both statistical–empirical and physically based methods are discussed. Subsequently, the prevailing techniques of assimilating remote sensing data into agroecosystem models are outlined. The increasing complexity of data assimilation methods and of models describing agroecosystem functioning has significantly increased computational demands. For this reason, we include a short section on the potential of parallel processing to deal with the complex and computationally intensive algorithms described in the preceding sections.The studied literature reveals that many valuable techniques have been developed both for the retrieval of canopy state variables from reflective remote sensing data as for assimilating the retrieved variables in agroecosystem models. However, for agroecosystem modeling and remote sensing data assimilation to be commonly employed on a global operational basis, emphasis will have to be put on bridging the mismatch between data availability and accuracy on one hand, and model and user requirements on the other. This could be achieved by integrating imagery with different spatial, temporal, spectral, and angular resolutions, and the fusion of optical data with data of different origin, such as LIDAR and radar/microwave.     

遥感数据融合的进展与前瞻

数据融合是提升遥感影像应用能力的重要手段,一直是遥感信息处理与应用领域的研究热点。本文系统综述了遥感数据融合的进展与前瞻:首先对数据融合的层次与分类进行了总结和归纳,将遥感数据融合划分为同质遥感数据融合、异质遥感数据融合、遥感—站点数据融合、遥感—非观测数据融合4大类;在此基础上,重点针对时—空—谱光学遥感数据的融合,从多视超分辨率融合、多尺度融合、空—谱融合、时—空融合、时—空—谱一体化融合等方面进行了详细阐述;最后总结了遥感数据融合的前瞻研究方向,包括时—空—谱一体化融合的拓展、空天地观测数据的跨尺度融合、传感网环境下的在线融合、面向应用的融合方法等。     

遥感影像数据仓库及网络服务探讨

通过较为先进的数据库技术进行影像数据的存储与管理,便于数据的查询、浏览、分析等功能的实现,并为影像数据的发布与共享提供条件;利用遥感影像元数据实现遥感数据的网络发布与共享,从而使稀缺的影像数据能够得到充分合理的利用;同时采用本体技术,可以有效的实现影像数据的互操作,从而为实现影像数据的全社会范围的共享提供基础与条件。     

发展几何光学遥感建模理论，推动定量遥感科学前行——深切缅怀李小文院士

李小文长期致力于遥感基础研究,是植被几何光学遥感建模的先驱。他创建了Li-Strahler几何光学模型,论文入选"国际光学工程学会(SPIE)"里程碑系列文集。以李小文为首席科学家,带领国内外科学团队,在植被二向性反射建模、热红外遥感辐射方向性建模、遥感信息尺度效应、定量遥感综合实验与真实性检验方面做出了卓越成就。本文总结了李小文的主要学术思想,对定量遥感相关研究进展进行了总结和回顾,对遥感科学及相关领域具有重要的借鉴和参考意义。     

多源遥感与作物模型同化模拟作物物生长参数时空域连续变化

本文将遥感信息与作物模型同化实现作物生长参数的时空域连续模拟,进而监测生长参数的时空域变化.首先将作物模型WOFOST(World food studies) 与冠层辐射传输模型PROSAIL 耦合构建WOPROSAIL 模型,利用微粒群算法(PSO) 通过最小化从CCD 数据获取的土壤调节植被指数观测值SAVI(soil adjusted vegetation index) 与耦合模型得到的模拟值SAVI’之间差值优化作物模型初始参数.通过MODIS 数据反演实现参数的区域化,并将区域参数作为优化后作物模型输入参数驱动模型逐像元计算生长参数,实现生长参数的时空域连续模拟与监测,最终建立区域尺度遥感-作物模拟同化框架模型RS-WOPROSAIL .结果表明：同化模型解决了作物模型模拟空间域和遥感信息时间域的不连续问题.模型模拟的叶面积指数(LAI) 、穗重(WSO) 、地上总生物量(TAGP) 等生长参数较好地体现了水稻生长状况时空域变化,研究区水稻模拟产量与实际产量的误差为27.4% .     

Study of morphology and suspended sediment of Bhopal Upper Lake using spatial simulation technique and remote sensing data

The scope of this research was to study lake morphology using spatial simulation technique, to develop revised elevation-capacity curve, to develop elevation-water spread area curve, to study the relation between suspended sediment and remote sensing satellite data, and to estimate suspended sediment load in the lake using a Geographic Information System coupled with ground truth. The study area was the Bhopal Upper Lake, which has been classified as one of the major wetlands in India by the Ministry of Water Resources, India. A precise digital elevation model was created using 0.5 meter interval contour information collected from bathometric surveys. Water-spread areas at different water levels were simulated spatially in a Geographic Information System (GIS) through the neighbourhood connectivity operator. Revised elevation-capacity curve and elevation-area curve of the lake were prepared using the simulated results. Simulated water spread area at full tank level (FTL) was compared with the actual water spread area delineated using remote sensing data. Water samples at different locations of the lake were collected and located using the Global Positioning System (GPS) instrument. These samples were analysed in the laboratory for suspended sediment concentration. Different image processing techniques were applied to LANDSAT 5 TM satellite digital data (except thermal band). Correlation between radiance values of band 2 and suspended sediments was established and a positive linear equation was found to fit the data best. Spatial distribution of suspended sediment load was estimated using the developed regression equation and band 2 radiance image of the complete lake. Total suspended sediment load and loss of capacity at full tank level were computed.     

矢量数据辅助的高分辨率遥感影像道路自动提取

高分辨率遥感影像上细节信息繁杂、干扰物普遍存在,对其进行自动化道路识别与提取的相关研究仍处在探索阶段。在道路提取过程中引入矢量数据辅助,可解决初始信息获取的困难,得到可靠性较强的训练样本。为此,提出一种矢量数据辅助下的道路提取方法,能够筛选出矢量数据中包含的有效信息,引导实现对高分辨率遥感影像的道路自动提取。利用Mean-shift滤波对图像进行预处理后,首先从矢量数据获取候选种子点,并通过提炼同质区域的形状特征剔除错误候选点;然后,自动获取负样本点以进行朴素贝叶斯分类,并采用邻域质心投票算法从分类影像提取道路中心线;最后,结合像素跟踪与方向判断矢量化道路中心线,并提出一种基于矢量几何分析的断线连接与毛刺剔除方法,对提取结果进行信息修复与规整、优化。实验结果显示,该算法的提取质量达到80%以上,且具备较强的稳健性,能够适应具有不同道路辐射和分布特征的高分辨率遥感影像。     

Forest cover monitoring using remote sensing and GIS — A case study in Dhaulkhand range of Rajaji National Park,Uttar pradesh

Rajaji National Park in U.P. is a protected area where large number of nomad population live within the park area. Their dependence on the forest for cattle rearing and firewood has caused degradation of the forests. Proximity to settlements outside the park further adds to the problems. In the present study, forest cover and river, bed changes have been attempted by using temporal aerospace data of the year 1960 and 1993. Subsequently, PAMAP GIS package has been used for the change detection analysis. The study indicates that the land cover changes are mainly due to biotic factors. Some of the important changes in forest cover are: (i) transformation of mixed forest to scrub forest in 67 ha (ii) the sal mixed and mixed sal forest categories have replaced sal forest in 262 ha (iii) significant increase in forest plantation i.e. 2075 ha in the year 1960 to 3793 ha in 1993 (iv) eighteen times increase in Chirpine area, it increased from 13 ha in 1960 to 230 ha in 1993. The land cover changes in 6663 ha (45%) out of 14962 ha of the study area. The consequential changes in the river beds due to the change in the forest cover was also analyzed. During this period river beds with boulders have increased by 87 ha. These river bed changes include lengthening and broadening of river and change in river course.     

A filtering approach for estimating lake water quality from remote sensing data

In this paper we consider the estimation of lake water quality constituent distributions from hyperspectral remote sensing data. We present a computational approach that can be used to assimilate information from mathematical evolution models into data processing. The method is based on a reduced order iterated extended Kalman filter, and a convection–diffusion model is used to describe the movement of the water quality constituents. The performance of the technique is evaluated in a simulation study. The results show that the filter approach with an appropriate evolution model yields estimates that have better spatial and temporal resolutions than those obtained with conventional methods. Furthermore, the use of a feasible evolution model may make it possible to obtain information also on the concentrations in the lower parts of the lake.     

面向对象的遥感影像时空特征模型研究

对遥感影像的影像对象进行时空特征分析是遥感影像的智能分析与解译的基础,现有的时空数据模型不能满足影像对象时空特征分析的需要。文中基于遥感影像多尺度分割产生的影像对象用面向对象的方法建立时空特征数据模型,此模型可以满足对象存储和基于时间、空间、特征、属性查询的需要。同时,将此模型应用于遥感影像中海岸线与海岸带地物的时空特征建模,并验证模型的有效性。     

植被光合有效辐射吸收比率遥感研究进展

植被光合有效辐射吸收比率FPAR（Fraction of absorbed Photosynthetically Active Radiation）反映了植被冠层的光学特性,是表征植被光合作用水平和生长状态的重要参量,因此成为全球变化研究中多种过程模型的重要输入参数。随着定量遥感研究的深入和新型传感器的使用,从区域到全球尺度上的FPAR遥感估算方法不断提出,多样化的遥感FPAR产品越来越多地应用于碳循环、能量循环、生产力估算及作物估产等研究领域。本文梳理了遥感估算的植被光合有效辐射的相关概念和算法,并着重对过去十年间遥感估算FPAR的新进展进行了系统总结和探讨。研究表明,近年来FPAR遥感的研究工作一方面聚焦于对现有算法的改进与各类型产品的验证,更多的研究则侧重于FPAR概念体系的拓展,叶片、叶绿素水平的FPAR估算,直射光、散射光的FPAR建模等新方向逐渐成为研究热点。     

典型遥感数据分类方法的适用性分析——以遥感图像场景分类为例

目前普遍采用的分类器通常都是针对单一或小量任务而设计的,在小数据量的处理中能取得比较满意的结果。但对于海量遥感数据的处理,其在处理时效和分类精度方面还有待研究。本文以遥感图像场景分类任务为例,着重对遥感数据分类问题中几种典型分类方法的适用性进行比较研究,包括K近邻(KNN)、随机森林(RF),支持向量机(SVM)和稀疏表达分类器(SRC)等。分别从参数敏感性,训练样本数据量,待分类样本数据量和样本特征维数对分类器性能的影响等几个方面进行比较分析。实验结果表明:(1)KNN,RF和L0-SRC方法相比RBF-SVM,Linear-SVM和L1-SRC,受参数影响的程度更弱;(2)待分类样本固定的情况下,随着训练样本数目的增加,SRC类型分类方法的分类性能最佳,SVM类型方法次之,然后是RF和KNN,在总体分类时间上呈现出L0-SRCL1-SRCRFRBF-SVM/Linear-SVMKNN/L0-SRC-Batch的趋势;(3)训练样本固定的情况下,所有分类方法的分类精度几乎都不受待分类样本数目变化的影响,RBF-SVM方法性能最佳,其次是L1-SRC,然后是Linear-SVM,最后是RF和L0-SRC/L0-SRC-Batch,在总体分类时间上,L1-SRC和L0-SRC相比其他分类方法最为耗时;(4)样本特征维数的变化不仅影响分类器的运行效率,同时也影响其分类精度,其中SRC和KNN分类器器无需较高的特征维数即可获得较好的分类结果,SVM对高维特征具有较强的包容性和学习能力,RF分类器对特征维数增加则表现得并不敏感,特征维数的增加并不能对其分类精度的提升带来更多的贡献。总的来说,在大数据量的遥感数据分类任务中,现有分类方法具有良好的适用性,但是对于分类器的选择应当基于各自的特点和优势,结合实际应用的特点进行权衡和选择,选择参数敏感性较小,分类总体时间消耗低但分类精度相对较高的分类方法。     

月球遥感制图回顾与展望

对月球探测任务、月球遥感制图技术与产品进行综述。从1958年开始,全世界已开展126次(其中70次成功)月球探测工程任务,其中月球遥感制图是其必需的基础性工作。由于月球环境的特殊性,其遥感制图技术与对地观测制图相比具有很大的挑战和更大的难度。目前,中国嫦娥二号轨道器获取的7 m分辨率立体影像是覆盖全月球分辨率最高的立体影像数据,美国月球侦察轨道器LRO任务的激光雷达高度计LOLA数据是精度和密度最高的激光测高数据,LRO NAC影像的分辨率最高(0.5—2 m)但未覆盖全球。在各个探测任务中,基于月球遥感数据和摄影测量技术,已经制作了大量的全球及区域的影像拼图、正射影像图和数字高程模型等制图产品。对月球遥感制图技术发展进行展望,探讨了利用国际多探测任务数据建立新一代控制网和进行精细制图的必要性及技术思路。     

行星遥感影像目标识别与分类进展

从行星遥感海量数据中对地形地貌特征进行识别和分类,是行星科学研究中的一项重要基础工作.本文综述了自实施月球和深空探测任务以来,国际、国内采用行星影像数据进行地形地貌识别与分类技术的研究进展.首先,从月球、火星以及其他行星探测任务3个方面,对相关的探测任务和获取的影像数据进行简介.然后,在介绍通用目标识别与分类方法研究进...     

Landsat8卫星遥感数据预处理方法

Landsat系列卫星是由美国航空航天局和美国地质调查局共同管理的资源遥感系列卫星,40多a来为地球遥感探测活动提供了大量清晰而稳定的图像数据。卫星遥感数据预处理是获取优质遥感基础图像的第一步,对后续各级卫星遥感产品的质量有着很重要的影响。针对Landsat8卫星原始数据,对卫星下传所采用的空间数据传输协议和数据传输格式进行了详细的解析,分析了原始数据从解同步、数据帧解析、任务数据包解析、图像数据获取直到生成0级图像产品的步骤;特别针对存在无损数据压缩的陆地成像仪(operational land imager,OLI)数据,讨论了基于空间数据系统咨询委员会(consultative committee for space data systems,CCSDS)相关标准进行无损数据解压缩处理的方法和过程。经数据预处理得到的Landsat8卫星0级图像产品,可为Landsat8卫星数据应用提供优质的基础图像。     

遥感时间序列数据滤波重建算法发展综述

遥感时间序列数据(MODIS,NOAA/AVHRR,SPOT/VEGETATION等)在植被生长监测、物候信息提取、土地利用类型监测等诸多领域得到了广泛应用,是生产研究的重要数据源之一.由于传感器、云层大气等影响,遥感时间序列数据存在着严重的噪声,应用前必须进行序列滤波重建工作.综述现有各类滤波重建方法,对研究中广为采用的3类主要方法(基于最小二乘的非对称高斯函数拟合、SavitZky-Golay滤波、基于离散傅里叶的系列分析方法)集中阐述其理论基础、应用步骤和优缺点.总结当前遥感时间序列滤波重建方法需要进一步改进之处.     

基于GeoRaster的多源遥感数据存储研究

遥感数据源极大丰富,影像文件格式多样,组织方式也较复杂,如何采用统一的接口实现异构多源海量遥感数据的存储是一大难题。本文以多源遥感数据的存储为研究对象,在研究Oracle GeoRaster数据模型的基础上,设计了扩展的基于GeoRaster的多源遥感影像存储模型,利用java JAI与GDAL相结合,实现了多源多格式遥感影像数据的统一存储。